Comparison of face pressurized shield methods in various soil conditions

Up to the present time the Wayss & Freytag Ingenieurbau AG has completed more than 127 km of tunnelling using different tunnelling methods. Shielded tunnels, tunnels using conventional methods as well as immersed tunnels were constructed in different countries nearly all over the world. Over the last 30 years most of the important developments concerning the machine technology for EPB- and Slurry-Shields have taken place. Since the first application of a hydroshield for the Wilhemsburg Collector project in Hamburg in the early seventies, several steps of development have led to the current state-of-the-art in mechanised tunnelling. The continuous improvement of TBM techniques allows the execution of high quality tunnelling particularly with regard to maximum safety and efficiency. The practical experience of the construction companies are an essential basis for continued development. After all, the performance risk of tunnelling is usually borne by the contractors. The first application of a hydroshield was in the early seventies on the project Wilhelmsburg interceptor sewer in Hamburg. The hydroshield was an evolutionary concept in shield design which blazed new trails in the difficult field of tunnelling in sub aqueous or water bearing soils. The essential features of the hydroshield method were sensitive control of the pressure of the supporting fluid by means of a compressed air cushion, high capacity hydraulic transport of the excavated soil and recycling of the supporting fluid and, above all, no use of compressed air behind the sealed bulkhead of the cutter chamber within the tunnel. Since this first use of a hydroshield, several steps of development have taken place and led to the current state-of-the-art. At present a lot of TBMs are equipped with integrated stone crushers, horizontally movable supporting plates and a centre cutter. Each application of mechanised shield tunnelling requires an individual solution in order to reach the best result and highest quality. In many cases these solutions cannot be found in a conventional application of common techniques but very often in additional improvements of details. The pros and cons of Slurry and EPB tunnelling have to be compared and evaluated. Under certain mixed face conditions the application of a hydroshield can have decisive advantages compared to an EPB shield and its application is preferred. One such situation can be the occurrence of mixed ground conditions at the working face in terms of hard rock at the bottom and soft soil at the top of the face. With an EPB shield these conditions can lead to insufficient face support. (A). "Reprinted with permission from Elsevier". For the covering abstract see ITRD E124500.

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  • Accession Number: 01011580
  • Record Type: Publication
  • Source Agency: Transport Research Laboratory
  • Files: ITRD
  • Created Date: Dec 19 2005 3:18PM